User terminal and radio communication method

Abstract

The present invention is designed so that the transmission of A/Ns can be controlled properly when the reference value for the timing for transmitting signals is controlled in radio base stations and/or user terminals. A user terminal, according to the present invention, has a receiving section that receives a downlink (DL) shared channel, and a control section that controls transmission of retransmission control information in response to the DL shared channel. The control section controls the transmission of the retransmission control information based on a reference value that is configured for timing for transmitting the retransmission control information.

The invention claimed is: 
     
       1. A terminal comprising:
 a receiver that receives a downlink (DL) shared channel; 
 a processor that determines a reference value for a transmission timing of retransmission control information in response to the DL shared channel based on indication information configured by higher layer signaling; and 
 a transmitter that transmits the retransmission control information based on the reference value, 
 wherein the indication information includes a one or more prospective values to be the reference value, and 
 wherein a number of bits in a given field of downlink control information (DCI) to schedule the DL shared channel is determined based on the number of prospective values. 
 
     
     
       2. A radio communication method for a terminal, comprising:
 receiving a downlink (DL) shared channel; 
 determining a reference value for a transmission timing of retransmission control information in response to the DL shared channel based on indication information configured by higher layer signaling; and 
 transmitting the retransmission control information based on the reference value, 
 wherein the indication information includes a one or more prospective values to be the reference value, and 
 wherein a number of bits in a given field of downlink control information (DCI) to schedule the DL shared channel is determined based on the number of prospective values. 
 
     
     
       3. A base station comprising:
 a transmitter that transmits a downlink (DL) shared channel, and transmits indication information, by higher layer signaling, that indicates a reference value for a transmission timing of retransmission control information in response to the DL shared channel; and 
 a processor that controls to receive the retransmission control information transmitted based on the reference value, 
 wherein the indication information includes a one or more prospective values to be the reference value, and 
 wherein a number of bits in a given field of downlink control information (DCI) to schedule the DL shared channel is determined based on the number of prospective values. 
 
     
     
       4. A system comprising a base station and a terminal, wherein:
 the base station comprises:
 a first transmitter that transmits a downlink (DL) shared channel, and transmits indication information, by higher layer signaling, that indicates a reference value for a transmission timing of retransmission control information in response to the DL shared channel; and 
 a first processor that controls to receive the retransmission control information transmitted based on the reference value, and 
 
 the terminal comprises:
 a receiver that receives the DL shared channel; 
 a second processor that determines the reference value based on the indication information; and 
 a second transmitter that transmits the retransmission control information based on the reference value, 
 wherein the indication information includes a one or more prospective values to be the reference value, and 
 
 wherein a number of bits in a given field of downlink control information (DCI) to schedule the DL shared channel is determined based on the number of prospective values.